Electrical connector



Aug. 31, 1965 J. EISERT 3,204,214

ELECTRICAL CONNECTOR Filed April 26, 1965 3 Sheets-Sheet 1 INVENTOR JOSEF EISERT W W AGENT 1, 1965 J. EISERT 3,204,214

ELECTRICAL CONNECTOR Filed April 26, 1965 3 Sheets-Sheet 2 JOSEF EISERT INVENTOR.

Y BY AGENT Aug. 31, 1965 J. ElSERT ELECTRICAL CONNECTOR 5 Sheets-Sheet 3 Filed April 26, 1965 Fig 'l2 Fig 13 JOSEF EISERT INVENTOR United States Patent 3,204,214 ELECTRICAL CONNECTOR Josef Eisert, am Ruhrstein 37, Essen, Germany Filed Apr. 26, 1963, Ser. No. 275,949 3 Claims. (Cl. 339-95) My present invention relates to electrical connectors and, more particularly, to so-called plug-and-jack connectors wherein a male member and a female member are relatively displaceable for making and breaking electric contact.

It is known to provide plug-and-jack connectors of the aforedescribed character wherein the female member is composed of resilient sheet metal and is formed with a pair of clamping portions adapted to bear against a male member inserted into the sleeve. These clamping portions are spread by the male member and serve to make electrical contact therewith. The difiiculties arising in connection with such structures are well known; for example, it is important to maintain a substantially constant contact pressure between the interengaging parts of the male and female members to avoid the interposition of oxides, soot and other materials between the contact surfaces and thus prevent voltage drops across the contact interface, and to eliminate as far as possible, metal fatigue of the resilient members. It has, therefore, been proposed to provide female members Whose sleeve portions are formed by bent springs, the ends whereof are juxtaposed and serve as contacts engageable with the male member. In general, these ends of the spring elements serve either as the sole means of conducting electric current between the male and female members or as carriers for at least a substantial proportion of the current flow. I have found that, to a large degree, the disadvantages of earlier plug-and-jac-k connectors of this general type are due to the fact that a substantial part of the current flow takes place through the spring elements serving as clamping means and as contacts for making and breaking the electric circuit. Especially when the sleeve is constructed of sheet material, the current flow to the contact ends heats the spring members to a certain degree, most significantly upon the passage of large currents through the circuit, and thus reduces the mechanical strength of the spring elements in addition to renderingthem susceptible to metal fatigue.

It will be appreciated that leaf springs in general and flat resilient contact members in particular are disadvantageously influenced by elevated temperatures whether generated electrically or by any other means. In this connection, it may be pointed out that high-current flows through a plug-and-jack connector of the type described will almost invariably cause heating of the spring elements and a loss of resilience. Moreover, short-circuiting in the extermal circuit is not always necessary to cause deterioration of the spring elements. When the plug-and-jack connector is used as a switch to energize a load having high-current drain, significant heating will be noted. Additionally, gradual insertion of the plug into the jack will almost invariably result in a concentration of the current flow through small portions of the spring elements, thereby increasing the heating effect at these locations. These deficiencies are ex ceptionally important when the plug-and-jack connector serves to connect a load to a high-power battery or the like.

Further disadvantages of known plug-and-jack connectors employing sheet-metal sleeves derive, to a large extent, from the fact that the spring and contact elements of these devices, which are usually composed of brass, copper or stainless steel, cannot be readily provided with thin layers of noble contact metals capable 3,204,214 Patented Aug. 31, 1965 of withstanding corrosion and providing low-resistance electrical junctions. The use of such layers is particularly desirable in situations wherein the contact surfaces may be subjected to chemical deterioration and the development of so-called contact potentials as a consequence of the use of different materials along the contact surfaces of the male or female members. When noble metals such as silver, gold, platinum, rhodium, iridium and tungsten are employed along the contact portions of both connector members, such contact potentials can be eleminated.

It is an object of the present invention to provide an electrical connector of the plug-and-jack type wherein the aforementioned disadvantages are obviated.

Another object of this invention is to provide an electrical connector which can be formed with contact strips of a noble metal.

Still another object is to provide a connector of this character which is insensitive to high currents and is capable of withstanding short-circuit current flows.

According to one aspect of the present invention, a lug-and-jack connector comprises a female member having a sleeve composed of relatively resilient sheet material which is conductive at least along a central strip lying in an axial plane of the sleeve and extending in the direction of insertion of the male member. It should be noted that the expression strip as used herein is intended to include continuous as well as discontinuous engaging surfaces. The male member is axially insertable into the sleeve which is provided with clamping portions, preferably integral with the sheet material const-ituting the sleeve, for urging the contact strip of the sleeve into engagement with the corresponding strip of the male member.

The clamping portions can extend outwardly from a central zone of the sleeve which constitutes the root or base thereof and has the contact strip extending therealong, the female member being provided with a conductor positioned along the central zone so that the latter carries the largest proportion of the current communicating between the sleeve and the member. It is clear, therefore, that there is substantially no distribution of current via the clamping portions since substantially all current is concentrated at the central zone. To ensure that there is no significant sensitivity of the connector to impurities disposed between the contact surfaces, the latter are so constructed and arranged as to be relatively narrow with the clamping means applying their full force to hold the sleeve against the male member with a constant contact pressure along these limited strips. The contact surfaces are restricted to provide line or only minor-surface contact and do not, preferably, parallel each other over any considerable surface area.

It is desirable that the sleeve be resiliently deformable only at locations remote from the contact strip (i.e. in the region of the clamping portions) so that there is little tendency for the sleeve to conform to the configuration of the male member. It may also be pointed out that the clamping portions of the sleeve should be so arranged that the force holding the sleeve against the male member is substantially uniform over the entire contact surface.

According to a more specific feature of the invention, the sleeve has a generally cylindrical configuration and the male member, which advantageously is provided with a central ridge lying in the aforementioned axial plane, is formed with retaining means shaped as ledges and positively engaged by the clamping portions of the sleeve. The latter are disposed symmetrically on opposite sides of the axial plane and bear inwardly upon the male member to force it into contact with the strip along the central zone of the sleeve. In this case, the bent ends of the sleeve, whose edges engage the male member, are

resilient but do not carry any substantial current so that there is very little heating effect. The spring or clamp elements can be partly separated from the remainder of the sleeve, with which they are integral, by axially spaced slots lying in planes transverse to the axis and perpendicular to the axial plane.

According to a further feature of the invention the sleeve is generally flanged or elongated so as to have a substantially oval configuration and is adapted'to receive a flat male member Whose tongue can extend axially into the sleeve perpendicularly to the axial plane. One face of the tongue will, consequently, confront the central zone of the sleeve while the other face serves as an abutment again-st which the clamping portions bear symmetrically. I have found that it is desirable to construct these clamping portions as inwardly turned, centrally directed flanges. As in the previous case, at least one of the members is provided with a ridge extending centrally along the member and constituting the respective contact strip. When a flat tongue is used as the plug, I prefer to arrange the ridge on the sleeve sothat this ridge can engage the tongue or blade along a knife edge. It has been found, however, that in some instances excellent results can be obtained when the ridge, of generally trapezoidal transverse cross-section, has a narrow flanged surface engaging the contact face of the tongue.

Yet another aspect of the present invention resides in the provision of contact layers of a noble metal along one or both of the cooperating contact strips. Advantageously, the noble metal can be inlaid or rolled onto the base metal and fusion-bonded thereto 'by resistance welding. By way of example, it may be noted that silver, cobalt, platinum, rhodium, iridium and tungsten strips have been found to be suitable for thispurpose. Any other conventional contact metals having the capacity to withstand chemical erosion andadapted to resist pitting influences would be suitable.

Furthermore, I have discovered that exceptionally convenient and satisfactory plug-and-jack connectors can be provided when the male member is formed with an abut ment surface lying in a plane. perpendicular to the aforementioned axialplane, means being provided to eliminate slippage of the clamping portions with respect to the abutment surface. When the surface is generally planar as is the case with a tongue or blade, these means are constituted by the abutment surface itself. They can also be constituted by ridges as indicated previously.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing wherein:

FIG. 1 is a plan view of a plug-and-jack connector according to the present invention;

FIG. 2 is a cross-sectional view taken along the line IIII of the FIG. 1;

FIG. 3 is a plan view of the socket or sleeve portion of the female connector in a spread or developed condition;

FIG. 4 is a bottom-plan view of a connector accordin to another embodiment of the invention;

FIG. 5 is a cross-sectional view taken along line VV of FIG. 4;

FIG. 6 is a topplan view of the connector;

FIG. 7 is a developed view of the sleeve of this connector;

FIG. 8 is a view similar to.FIG. 5 illustrating another modification;

FIG. 9 is a developed view of the sleeve of this modification;

FIG. 10 is a view similar to FIG. 2 illustratingstill another embodiment of the invention; 7

FIG. 11 is an elevational view of the male memberof the connector;

FIG. 12 is anotherwiew similar to FIG. 5 showing a modified connector;

FIG. 13 is a bot-tom view thereof; and

FIG. 14 is a top view of the female member of this connector.

In FIGS. 1 and 2 of the drawing I show a connector whose female member 10 comprises a shank 11, by which electrical connection is made to a conductor, and a sleeve 12 of generally cylindrical configuration. This sleeve is shown in developed form in FIG. 3. From this figure it may be observed that a plurality of slots or incisions 13 are provided in axially spaced relationship so that, when the sleeve-forming portion is bent into cylindrical shape, these slots lie in planes perpendicular to the axis. The slots also subdivide the bent ends of the sheet-metal sleeve into resilient clamping portions 14 whose extremities 15 (FIG. 2) are folded at right angles to the clampingportions 14 and are directed inwardly as well as toward the central zone 16 of the female member. The clamping flanges 15 are thus disposed symmetrically on opposite sides of an axial plane passing through the central zone. The plug or male member 17 has a generally flattened configuration and lies in this axial plane, being formed with a contact edge or ridge 18 of triangular cross-section. This knife edge forms a contact strip of the male member which engages the central zone or contact strip of the female member with substantially line contact along line 16' (see FIG. 3). The male member is also provided with an abutment surface 19 against which the clamping portions 15 exert the full extent of their pressure, thereby holding the male member against the female member at 16 with undiminishing force. The abutment surface 19 lies in a plane perpendicular to the axial plane and spaced above the contacting strips and is formed by a pair of ridges 20 inclined outwardly away from the contacting strips, the ridges being integral with the male member. The forward end 21 of the latter is of wedge-shaped configuration and is adapted to spread the beveled portions 22 ofthe sleeve or socket. This arrangement confines the current flow substantially to the central zone 16', see FIG. 3, whereat the current paths C to C corresponding to each of the clamping elements, are concentrated. .Moreover, the line contact between male and female members eliminates the difilculties arising from impurities sandwiched between contact surfaces. There is no heating of the spring elements since only a minimum current flows therethrough even upon short-circuiting of the'external circuit.

The present improvement will be appreciated to a greater extent when it is pointed out that earlier systems in volving generally fiat male members and cylindrical sleeves required the clamping elements to constitute the sole or at least the principal conductors of current and thus led to a decrease in their resilience and in the establishment of nonuniform conduct pressures. In instances wherein the flat male member was replacedby a cylindrical plug, other disadvantages ensued. The absence of a Well-defined (e.g. flat) abutment surface in these structures frequently caused variations in contact pressure with subsequent insertions. Furthermore arrangements wherein a cylindrical plug was held against a cylindrical sleeve by clamping members of this type almost invariably resulted in substantial deflection of the sleeve to conform to the contour of the plug. Tests have shown that such arrangements are unsatisfactory as a consequence of the fact that the extent of the contact surface varies with the method of insertion of the plug and that reproducible contact pressurescannot be obtained, the possibility of contamination of the interface being greatly increased.

' In FIGS. 4-7 I show anotherarrangement wherein the sleeve 32 of female member 30 is of flattened or oval configuration (see FIG. 5 and generally has the appearance of a capsule or the like. .In this case, thetongue 37 of the male member 38 is also flat but extends in a plane perpendicular to the vertical axial. plane of the connector. Again spring clamping elements 34Ican be provided by slotting the sheet-metal blank (FIG. .7) at 33 prior to bending it into the configuration illustrated .inFIG. 5. The

clamping elements 34 are again inwardly turned and directed toward a central ridge 36 of the sleeve. This ridge constitutes a contact strip lying in an axial plane of the sleeve and bearing against a central zone 38 of the tongue 38. In this case, the upper face 37' of the tongue constitutes an abutment surface whose well-defined shape prevents slippage of the contact elements 34 therealong.

The advantages of the structure shown in FIGS. 4 to 7 will best be appreciated upon a comparison thereof with a conventional connector having a flattened sleeve. In conventional connectors of this type the sleeve has a flattened portion in engagement with the tongue over a wide area, even coextensive with the latter in some instances, so that penetration of contaminants into the region of contact results in an increase of the contact resistance. This difliculty is eliminated by the use of a ridge in the structure of the present invention. Moreover, the contact elements of known devices effectively hold only the lateral edges of the tongue in a well-defined grip, thereby obviating the attainment of high specific contact pressures. In the structure of FIGS. 4-7 both spring elements hold the tongue against the ridge whose knife edge permits attainment of the necessary high specific pressure.

In FIGS. 8 and 9, I show an arrangement wherein the tongue 47 is provided with layers 49' and 49" of a contact metal along its central strip on each face of the tongue so that the latter can be reversed by 180 if desirable. These contact layers, of one of the metals enumerated above, can be bonded to the brass or stainlesssteel tongue by rolling, spray-deposition, welding, or other known techniques. Along its central zone or ridge 46, the sleeve 42 is likewise provided with a metal inlay 46 by similar techniques prior to the bending of the sleeve into its final shape.

FIGS. 10 and 11 show another arrangement wherein a cylindrical sleeve 52, similar to that shown in FIG. 2, is formed with a contact layer 56 along its central zone or contact strip 56. Again this layer is preferably applied prior to the bending of the sleeve blank into its cylindrical configuration. In this case, the male member 57 may be constituted of sheet metal bent into U-shape with a conductive layer 59 of a noble metal disposed at the bight of the U. The ridges 55 may be bent from the sheet metal as indicated in FIG. 11 and the body of member 57 is, therefore, integral therewith. The metal inlay 59 is formed on the blank of the male member before the bending there of by a rolling and/ or fusion-welding process.

In the connector of FIGS. 12-14, the sleeve 62 has a central ridge 66 of trapezoidal configuration with a narrow flat surface 66 hearing against the tongue 47 which, as previously described, can be provided with metal-inlay layers for better contact. The ridge 66 also carries a layer 66" of a contact metal, preferably applied prior to the formation of the ridge and the banding of the generally flattened sleeve. As shown in FIG. 14, this layer 66' can extend along the shank 61 of the female member to the point at which the conductor is secured thereto. When somewhat flattened ridges are employed, the surface pressure is reduced so that relatively thin contact strips can be used.

The invention described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the appended claims.

I claim:

1. An electrical connector comprising a female member having the configuration of a sleeve, said sleeve being provided with resilient inwardly turned clamping portions symmetrically disposed on opposite sides of an axial plane and separated by an axially extending gap; and an elongated male member axially insertable in said sleeve, said male member having a blade-shaped body extending gen erally in said axial plane and provided with a linear contact edge and with retaining ledges, extending outwardly away from said edge along opposite sides of said plane, said clamping portions engaging said ledges of said body and urging said edge of said male member against said female member along a line of contact, said members being conductive at least along said line of contact.

2. A connector as defined in claim 1 wherein said edge of said male member is defined by an axially extending ridge of triangular cross-section along said line of contact.

3. A connector as defined in claim 1 wherein said female member is provided with an axially extending layer along said line of cont-act, said layer being more conductive than the rest of said female member.

References Cited by the Examiner UNITED STATES PATENTS 2,763,848 9/56 Tuchel 339-258 2,765,452 10/56 Tuchel 339258 2,770,792 11/56 Batcheller 339-258 2,785,387 3/57 Batcheller 339-258 2,846,649 8/58 Hornauer 339 278 JOSEPH D. SEERS, Primary Examiner. 

1. AN ELECTRICAL CONNECTOR COMPRISNG A FEMALE MEMBER HAVING THE CONFIGURATION OF A SLEEVE, SAID SLEEVE BEING PROVIDED WITH RESILIENT INWARDLY TURNED CLAMPING PORTIONS SYMMETRICALLY DISPOSED ON OPPOSITE SIDES OF AN AXIAL PLANE AND SEPARATED BY AN AXIALLY EXTENDING GAP; AND AN ELONGATED MALE MEMBER AXIALLY INSERTABLE IN SAID SLEEVE, SAID MALE MEMBER HAVING A BLADE-SHAPED BODY EXTENDING GENERALLY IN SAID AXIAL PLANE AND PROVIDED WITH A LINEAR CONTACT EDGE AND WITH RETAINING LEDGES, EXTENDING OUTWARDLY AWAY FROM SAID EDGE ALONG OPPOSITE SIDES OF SAID PLANE, SAID CLAMPING PORTIONS ENGAGING SAID LEDGES OF SAID BODY AND URGING SAID EDGE OF SAID MALE MEMBER AGAINST SAID FEMALE MEMBER ALONG A LINE OF CONTACT, SAID MEMBERS BEING CONDUCTIVE AT LEAST ALONG SAID LINE OF CONTACT. 